Page 82 - CB1.3 Genetic Varation sciPAD

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82 CB 1.3 GENETIC VARIATION
USING KNOWLEDGE OF GENETICS
A Genome
A ‘genome’ is the full amount of genetic information that an
organism carries in its DNA. All living things have genomes. The
genome contains all of the information needed to build that
organism and allow it to grow and develop. Think of a genome
as an instruction manual for an organism, but the text inside the
manual is just a long list of nucleotide bases: A, T, C and G’s.
The Human Genome Project (HGP) was a landmark global
scientific effort with the goal of generating the first sequence
of bases for the human genome. The HGP began in 1990
and was completed in 2003. The HGP found that humans
have approximately 20,000 – 25,000 genes which contain
approximately 3 billion base pairs (A - T and C - G).
The HGP is important because:
•
the total number and location of genes in the human genome was determined, allowing
scientists to investigate how each gene works.
•
it helps scientists search for genes that are linked to different types of genetic diseases. This
allows scientists to identify people at risk of developing that disease.
•
it helps scientists to understand and develop gene therapy for the treatment of inherited
disorders.
•
information from the HGP can be used to trace human migration patterns from the past, and
helps scientists to understand human evolution.
Besides the human genome, scientists continue to map the genomes of many other species.
As well as being useful in itself, mapping their genomes helps us to understand more about the
human genome because all living things share some of the same genes and DNA patterns.
Bacteria
Escherichia coli
~4 500 genes
Chicken
Gallus gallus
~17 000 genes
Fruit Fly
D. melanogaster
~14 000 genes
Sunflower
Helianthus annuus
~55 000 genes
Water flea
Moina macrocopa
~31 000 genes
1. Describe a ‘genome’. 

2. Outline the goal of the Human Genome Project. 


3. Describe three main outcomes of the Human Genome Project. 





4. Determine if there is a correlation between the size of an organism and the size of its
genome. Justify your answer. 



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